A fiber array spectral translator (“FAST”) system when used in conjunction with a photon detector allows massively parallel acquisition of full-spectral images. A FAST system can provide rapid real-time analysis for quick detection, classification, identification, and visualization of the sample. The FAST technology can acquire a few to thousands of full spectral range, spatially resolved spectra simultaneously. A typical FAST array contains multiple optical fibers that may be arranged in a two-dimensional array on one end and a one dimensional (i.e., linear) array on the other end. The linear array is useful for interfacing with a photon detector, such as a charge-coupled device (“CCD”). The two-dimensional array end of the FAST is typically positioned to receive photons from a sample. The photons from the sample may be, for example, emitted by the sample, reflected off of the sample, refracted by the sample, fluoresce from the sample, or scattered by the sample. The scattered photons may be Raman photons.
In a FAST spectrographic system, photons incident to the two-dimensional end of the FAST may be focused so that a spectroscopic image of the sample is conveyed onto the two-dimensional array of optical fibers. The two-dimensional array of optical fibers may be drawn into a one-dimensional distal array with, for example, serpentine ordering. The one-dimensional fiber stack may be operatively coupled to an imaging spectrograph of a photon detector, such as a charge-coupled device so as to apply the photons received at the two-dimensional end of the FAST to the detector rows of the photon detector.
One advantage of this type of apparatus over other spectroscopic apparatus is speed of analysis. A complete spectroscopic imaging data set can be acquired in the amount of time it takes to generate a single spectrum from a given material. Additionally, the FAST can be implemented with multiple detectors. The FAST system allows for massively parallel acquisition of full-spectral images. A FAST fiber bundle may feed optical information from its two-dimensional non-linear imaging end (which can be in any non-linear configuration, e.g., circular, square, rectangular, etc.) to its one-dimensional linear distal end input into the photon detector.
Given the advantageous ability of a FAST system to acquire hundreds to thousands of full spectral range, spatially-resolved spectra, such as Raman spectra, substantially simultaneously, a FAST system may be used in a variety of situations to help resolve difficult spectrographic problems such as the presence of polymorphs of a compound, sometimes referred to as spectral unmixing. As is known in the art, polymorphs may typically have a unique spectrum, such as a Raman spectrum, and the ability to rapidly determine the existence, or non-existence, of one or more polymorphs is essential to ensure, for example, the safety of a given compound when certain polymorphs may be hazardous to personnel and/or equipment.
Accordingly, it is an object of the present disclosure to provide a method for spectral unmixing, comprising obtaining a first spectrum of a mixture containing polymorphs of a compound using a photon detector and a fiber array spectral translator having plural fibers, providing a set of second spectra wherein each spectrum of said set of second spectra is representative of a different polymorph of said compound, comparing said first spectrum with said set of second spectra, and determining the presence of one or more polymorphs in said mixture based on said comparison.
It is another object of the present disclosure to provide a system for spectral umixing, comprising a photon source for illuminating with first photons a mixture containing polymorphs of a compound to thereby produce second photons, a fiber array spectral translator having plural fibers, wherein said fiber array spectral translator receives said second photons, a photon detector operatively connected to said fiber array spectral translator, wherein said photon detector detects said second photons to thereby obtain a first spectrum, and a microprocessor unit operatively connected to said photon detector and to a memory unit, wherein said memory unit stores a set of second spectra wherein each spectrum of said set of second spectra is representative of a different polymorph of said compound, and wherein said microprocessor compares said first spectrum with said set of second spectra to thereby determine the presence of one or more polymorphs in said mixture based on said comparison.
It is a further object of the present disclosure to provide a method for spectral umixing, comprising obtaining a first spectrum of a mixture containing polymorphs of a compound using a photon detector and a fiber array spectral translator having plural fibers, wherein said first spectrum is obtained from one of said plural fibers, providing a set of second spectra wherein each spectrum of said set of second spectra is representative of a different polymorph of said compound, comparing said first spectrum with said set of second spectra using a linear spectral unmixing algorithm, determining a set of mixture coefficients to thereby determine the presence of one or more polymorphs in said mixture, determining a goodness-of-fit factor and comparing said goodness-of-fit factor to a predetermined threshold, and determining the presence of an unknown substance in said mixture if said goodness-of-fit factor is less than said predetermined threshold.
It is yet a further object of the present disclosure to provide a system for spectral unmixing, comprising a photon source for illuminating with first photons a mixture containing polymorphs of a compound to thereby produce second photons, a fiber array spectral translator having plural fibers, wherein one fiber of said fiber array spectral translator receives said second photons, a photon detector operatively connected to said one fiber of said fiber array spectral translator, wherein said photon detector detects said second photons to thereby obtain a first spectrum, and a microprocessor unit operatively connected to said photon detector and to a memory unit, wherein said memory unit stores a set of second spectra wherein each spectrum of said set of second spectra is representative of a different polymorph of said compound, and wherein said microprocessor includes circuitry for comparing said first spectrum with said set of second spectra using a linear spectral unmixing algorithm to thereby determine a set of mixture coefficients so as to determine the presence of one or more polymorphs in said mixture based on said comparison, circuitry for determining a goodness-of-fit factor and comparing said goodness-of-fit factor to a predetermined threshold, and circuitry for determining the presence of an unknown substance in said mixture if said goodness-of-fit factor is less than said predetermined threshold.
It is still a further object of the present disclosure to provide a system for spectral unmixing, comprising a photon source for illuminating with first photons a mixture containing polymorphs of a compound to thereby produce second photons, a fiber array spectral translator having plural fibers, wherein one fiber of said fiber array spectral translator receives said second photons, a photon detector operatively connected to said one fiber of said fiber array spectral translator, wherein said photon detector detects said second photons to thereby obtain a first spectrum, and a microprocessor unit operatively connected to said photon detector and to a memory unit, wherein said memory unit stores a set of second spectra wherein each spectrum of said set of second spectra is representative of a different polymorph of said compound, and wherein said microprocessor runs a software program for comparing said first spectrum with said set of second spectra using a linear spectral unmixing algorithm to thereby determine a set of mixture coefficients so as to determine the presence of one or more polymorphs in said mixture based on said comparison, determining a goodness-of-fit factor and comparing said goodness-of-fit factor to a predetermined threshold, and determining the presence of an unknown substance in said mixture if said goodness-of-fit factor is less than said predetermined threshold.